Thunderbird 78.5.0 stopped connecting

Everything was fine Sunday the 29th but Monday nothing works.
I have tried everything suggested and still nothing.


I have the same problem. It may be because dreamhost updated their mail certificates this weekend and they now expire 06-dec-2021. I have not seen a description in their knowledgebase on how to update Thunderbird properly to make it work again.

Sidenote: to send this message, I had to sign up for the forum and accept a confirmation email. Haha, great joke if the actual problem that email is currently not working because of dreamhost…

Moritz, I finally got it working. First I went to mozilla thunderbird support and found directions to change the SSL/TSS security level. That did nothing.
Then I went tom my Eset Cyber security controls and got into the email settings and shut off the SSL filtering. That allowed me to connect.
Hope this helps.

Same problem here. Deleting and re-adding the email account to Thunderbird appears to be what ultimately fixed it. Obviously use caution to not lose any mail but I think this can be done safely.

I first/concurrently tried the setting the hidden configuration option security.tls.version.min to 1 and restarting. I’ve since reset that back to the default (3) and it still works, so I don’t think that was the problem.

As a clue, when I sent an email during this phase I had to re-accept the new SSL certificate. Sending worked fine after that. I theorize that perhaps the IMAP server SSL certificate needed to be re-accepted but Thunderbird either doesn’t know how to prompt you for this or has a bug.

Good luck!

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